14 DAY TRIAL // Most nitrogen pollutants released by humans into the Earth's atmosphere end up in the ocean, where they act as fertilizers and increase the production of marine plant life. This in turn determines a high absorption of carbon dioxide into oceanic sinkhole, according to a study carried out by Robert Duce, Atmospheric Science researcher and Distinguished Professor of Oceanography at the Texas A&M University.
Carbon dioxide is now believed to be the main cause for global warming. Reducing the carbon dioxide levels in the atmosphere would ultimately lead to a drop in the temperature increase rate. But there is a problem. Part of the nitrogen processed by the marine plant life is turned into a nitrogen compound called nitrous oxide, NOS or popularly known as laughing gas. Nitrous oxide is 300 times more powerful as greenhouse gas than carbon dioxide, thus the apparent reduction in carbon dioxide concentration in Earth's atmosphere is rescinded.
"But of course, the whole system is so complex that we're still rather unsure about what some of the other impacts might be within the ocean", Duce said.
Because nitrogen is a natural nutrient, once nitrogen concentration in a specific region of the ocean drops the respective area becomes unable to support life. Duce says that at least one-third of the total nitrogen deposits in the ocean are accounted as being caused by people, thus increasing the production of plant life. Furthermore, oceanic plant life is based on marine carbon which is in equilibrium with the carbon in the carbon dioxide gas in the atmosphere. Therefore an increase in marine plant life triggers the depletion of ocean carbon reserves which are then complemented by the absorption of carbon dioxide from the atmosphere.
"If you don't consider the impact of human-caused nitrogen when trying to model climate change, you're missing a possibly significant part of the overall carbon cycle as well as the nitrogen cycle. So nitrogen deposition is potentially a very important factor in the climate change issue", Duce said.
In 2000 alone, more than 54 million tons of nitrogen produced by mankind entered the ocean through the atmosphere and the quantity is rising every year. According to the team's calculations, by 2030 the nitrogen emissions will reach 62 million tons per year.
"Clearly, there is much that we do not know about the extent and timescale of the impacts of this nitrogen deposition on the oceans and the subsequent feedbacks to the climate system. The implications are complex and interactive, and this is a very important issue that policy makers need to address and that scientists trying to model and understand the future of climate and climate change need to take into consideration", said Duce.